I just started a 1956 DeSoto Fireflite that has been sitting for 5-8 years. According to both of the last two owners, the car was in a driveable condition when it was parked, at which time several projects were started that led to the hiatus. When I got it running this weekend (ran about 60 seconds total), it burped a little trans fluid out the dipstick tube and then that was followed by white smoke that smelled of burnt fluid coming out of the tube. Prior to starting the car, I had pulled the dipstick just to see if anything was in there and I got normal looking trans fluid on the dipstick. I will add that for the minute or so the car ran, I did not have coolant in the car as I just wanted to see if it started and ran first. I wouldn't think that the trans fluid would overheat in that short of time because of that, but now am second-guessing that assumption. I spoke with a friend who knows transmissions and his guess was either frozen bands or disintegrating clutches. Is there anything else that would cause these symptoms? Anything easy I can check before assuming the worst? Right now my first plan will be to pull the pan unless I figure out something easier to check first.

Your trans may have accumulated water over the years, and you may not have disturbed it when checking the fluid. Once the engine started, the water would get pumped and mixed with the trans fluid. It would boil off and produce white "smoke".

I have a good 1960 PowerFlite sitting on my shelf taking up space right now, come get it for free. I ran and drove the car before pulling this trans, it had no issues other than leaking due to hard, original seals.